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Index of Digital Elevation Models (DEM), New York

Identification Information
Citation
Originator
U.S. Geological Survey
Publication Date
unknown
Title
Index of Digital Elevation Models (DEM), New York
Geospatial Data Presentation Form
vector digital data
Publication Information
Publication Place
Reston, VA
Publisher
U.S. Geological Survey
Online Linkage
https://cugir.library.cornell.edu/catalog/cugir-008186
Abstract
This is an index of all the available DEM (digital elevation model) tiles within New York state. Download links are provided for each quad. Each DEM raster has a pixel resolution of approximately 10 meters. Elevation values were derived from USGS contour lines mapped at a scale of 1:24,000.
Purpose
DEMs can be used as source data for digital orthophotos and as layers in geographic information systems for earth science analysis. DEMs can also serve as tools for volumetric analysis, for site location of towers, or for drainage basin delineation. These data are collected as part of the National Mapping Program.
Supplemental Information
A Digital Elevation Model (DEM) contains a series of elevations ordered from south to north with the order of the columns from west to east. The DEM is formatted as one ASCII header record (A-record), followed by a series of profile records (B-records) each of which include a short B-record header followed by a series of ASCII integer elevations per each profile. The last physical record of the DEM is an accuracy record (C-record). The 7.5-minute DEM (10- by 10-m data spacing, elevations in decimeters) is cast on the Universal Transverse Mercator (UTM) projection (the quads UTM zone can be found in the header record (Record A)) in the North American Datum of 1927. It provides coverage in 7.5- by 7.5-minute blocks. Each product provides the same coverage as a standard USGS 7.5-minute quadrangle, but overedges are published as separate DEM files. Coverage is available for all quads completely contained within New York State, plus some additional ones falling along the borders and containing significant area of the State's land. 7.5-minute DEMs have rows and columns which vary in length and are staggered. The UTM bounding coordinates form a quadrilateral (no two sides are parallel to each other), rather than a rectangle. The user will need to pad out the uneven rows and columns with blanks or flagged data values, if a rectangle is required for the user's application. Some software vendors have incorporated this function into their software for input of standard formatted USGS DEMs.
Temporal Extent
Currentness Reference
process date
Time Instant
1995
Bounding Box
West
-79.75
East
-71.75
North
45.0
South
40.5
Theme Keyword
digital elevation model
digital terrain model
hypsography
altitude
topography
index map
Theme Keyword Thesaurus
None
ISO Topic Category
elevation
Theme Keyword
index map
elevation
Theme Keyword Thesaurus
CUGIR Category
Place Keyword
New York
Place Keyword Thesaurus
None
Temporal Keyword
Access Restrictions
None
Use Restrictions
1. The NYS DEC and the U.S. Geological Survey asks to be credited in derived products. 2. Secondary Distribution of the data is not allowed. 3. Any documentation provided is an integral part of the data set. Failure to use the documentation in conjunction with the digital data constitutes misuse of the data. 4. Although every effort has been made to ensure the accuracy of information, errors may be reflected in the data supplied. The user must be aware of data conditions and bear responsibility for the appropriate use of the information with respect to possible errors, original map scale, collection methodology, currency of data, and other conditions.
Status
Complete
Maintenance and Update Frequency
Irregular
Point of Contact
Contact Organization
New York State Department of Environmental Conservation. Division of Water
Delivery Point
625 Broadway
Delivery Point
4th floor
City
Albany
State
New York
Postal Code
12233-3500
Contact Telephone
518-402-8259
Contact Electronic Mail Address
watergis@gw.dec.state.ny.us
Native Data Set Environment
24,000 scale hypsographic contour linework drawn by photogrametric, plane table or other methods by USGS, US Army Corp of Engineers, Tennessee Valley Authority or others. Linework copied onto stable-base mylar. Raster image of linework created by USGS, Reston, with Optronics drum scanner at an aperture of 20um, to give an equivalent resolution of 1024 DPI. Raster data converted to vector with line-center algorithm in LT4X v. 3.1, 11/11/93, by John Dabritz of Infotec Development Inc. Grid elevations calculated with 8-profile weighted linear interpolation, with cubic smoothing of slope at the contour line as per algorithm in above mentioned LT4X v. - export in DEM format, UTM meters, - grid height and width of 10 mt, - clipping (overedge) coordinate in UTM mt, - input coord feet or meters (depending on source material), output in meters/decimeters, - DEM grid points which are on a profile section longer than 80 mt are smoothed by passing the grid through a low pass-filter twice. The filter size (see below) is of 9 cell diameters (aprox 9 mt). The purpose here is to leave well-contoured areas untouched while smoothing areas of less than 5-2.5% slope (to lessen streaking in flat areas typical of multiple-profile DEM derivation). - cubic smoothing of elevation profile across contours to 35% of the distance between adjacent contours. These profiles have a smaller, but still discontinuous change in slope at contour intersection than if not rounded. - 9 cell diameter for smoothing reach, - use all 8 directions (from grid point to N, S, E, W ,NE, NW, SE, SW) for each cell, - no line feeds. export dem contour data name 2 10.00 10.00 2 1 4 80 2 0.35 9 8 0
Cross-Reference
Originator
US Geological Survey
Publication Date
unknown
Title
Digital Elevation Model (DEM)
Online Linkage
http://eros.usgs.gov/guides/dem.html
Data Quality Information
Attribute Accuracy Report
10 mt gridding cell spacing is the maximun that can be meaningfully extracted from hypsography contour lines. This allows very good hypsographic contour reproduction in all areas except very flat ones. Elevation_resolution_ is 1 decimeter (0.1 meter). Elevation accuracy is 24,000 contour data, i.e. plus/minus half the contour interval.
Logical Consistency Report
The fidelity of the relationships encoded in the data structure of the DEM are automatically verified using a USGS software program upon completion of the data production cycle. The test verifies full compliance to the DEM specification.
Completeness Report
DEM visually inspected using Delta3D version 2.0, 1995 by John Dabritz and S. Phan of Infotec Development Inc. Checked for completness and drainage characteristics matching the USGS Hydrography Digital Line Graphs published at the same time as the model. Further validation for logical consistency performed previous to submission for archiving.
Horizontal Positional Accuracy Report
The horizontal accuracy of the DEM is expressed as an estimated root mean square error (RMSE). The estimate of the RMSE is based upon horizontal accuracy tests of the DEM source materials with equal to or less than intended horizontal RMSE error of the DEM. The testing of horizontal accuracy of the source materials is accomplished by comparing the planimetric (X and Y) coordinates of well-defined ground points with the coordinates of the same points as determined from a source of higher accuracy.
Quantitative Horizontal Positional Accuracy Assessment
Lineage
Source
Originator
U.S. Geological Survey
Publication Date
Unknown
Publication Time
Unknown
Title
Albany
Publication Information
Publication Place
EROS Data Center, SD
Publisher
U.S. Geological Survey
Type of Source Media
mylar separate from original color separation plate
Source Temporal Extent
Time Period Information
Single Date/Time
Calendar Date
unknown
Source Currentness Reference
ground condition
Contribution
elevation values for interpolation
Source
Originator
U.S. Geological Survey or National Geodetic Survey (NGS) (ed.)
Publication Date
Unknown
Publication Time
Unknown
Title
project control
Publication Information
Publication Place
EROS Data Center, SD
Publisher
U.S. Geological Survey
Type of Source Media
field notes
Source Temporal Extent
Time Period Information
Single Date/Time
Calendar Date
unknown
Source Currentness Reference
ground condition
Contribution
ground control points
Source
Originator
U.S. Geological Survey (ed.)
Publication Date
Unknown
Publication Time
Unknown
Title
photo ID number
Publication Information
Publication Place
EROS Data Center, SD
Publisher
U.S. Geological Survey
Type of Source Media
transparency
Source Temporal Extent
Time Period Information
Single Date/Time
Calendar Date
unknown
Source Currentness Reference
ground condition
Contribution
elevation values from photogrametry
Spatial Data Organization Information
Direct Spatial Reference Method
Vector
Point and Vector Object Information
SDTS Terms Description
SDTS Point and Vector Object Type
G-polygon
Point and Vector Object Count
961
Spatial Reference Information
Horizontal Coordinate System Definition
Planar
Grid Coordinate System
Grid Coordinate System Name
Universal Transverse Mercator
Universal Transverse Mercator
UTM Zone Number
17 or 18 or 19
Transverse Mercator
Scale Factor at Central Meridian
.9996
Longitude of Central Meridian
+075.000000
Latitude of Projection Origin
+00.000000
False Easting
0
False Northing
0
Planar Coordinate Information
Planar Coordinate Encoding Method
row and column
Coordinate Representation
Abscissa Resolution
10
Ordinate Resolution
10
Planar Distance Units
Meters
Geodetic Model
Horizontal Datum Name
North American Datum of 1927
Ellipsoid Name
Clarke 1866
Semi-major Axis
6378206.4
Denominator of Flattening Ratio
294.9787
Vertical Coordinate System Definition
Altitude System Definition
Altitude Datum Name
National Geodetic Vertical Datum of 1929
Altitude Resolution
1
Altitude Distance Units
decimeters
Altitude Encoding Method
Explicit elevation coordinate included with horizontal coordinates
Entity and Attribute Information
Entity and Attribute Overview
The digital elevation model is composed of an elevation value linked to a grid cell location representing a gridded form of a topographic map hypsography overlay. Each grid cell entity contains an 8-character value between -32,767.0 and 32,768.0.
Entity and Attribute Detail Citation
U.S. department of the Interior, U.S. Geological Survey, 1992, Standards for digital elevation models: Reston, VA, a hypertext version of the Digital Elevation Model (DEM) is available at: http://eros.usgs.gov/guides/dem.html (see Cross Reference)
Distribution Information
Format Name
GeoJSON
Format Name
metadata
Format Name
HTML metadata
Distributor
Albert R. Mann Library
Online Access
https://cugir-data.s3.amazonaws.com/00/81/86/cugir-008186-index.geojson
Online Access
https://cugir-data.s3.amazonaws.com/00/81/86/fgdc.xml
Online Access
https://cugir-data.s3.amazonaws.com/00/81/86/fgdc.html
Name
Metadata Reference Information
Metadata Date
20190524
Metadata Contact
Contact Information
Contact Organization Primary
Contact Organization
Albert R. Mann Library
Contact Address
Address
Albert R. Mann Library
City
Ithaca
State or Province
New York
Postal Code
14853
Country
USA
Contact Voice Telephone
607-255-5406
Contact Electronic Mail Address
mann-ref@cornell.edu
Metadata Standard Name
FGDC Content Standard for Digital Geospatial Metadata
Metadata Standard Version
FGDC-STD-001-1998
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